1. Field of the Invention
The present invention relates generally to methods of analyzing load-settlement characteristics of top-base foundations and, more particularly, to a method of analyzing load-settlement characteristics of a top-base foundation taking into account footing configuration and consolidation settlement depending on the kind of the ground.
2. Description of the Related Art
There is a lot of soft ground everywhere in the world. When construction for reinforcing such soft ground is conducted, an appropriate construction method for reinforcing soft ground is required to avoid problems of insufficient bearing capacity and settlement which may disturb the construction. However, over-design construction methods, such as deep foundation work, a soft-ground treatment method, etc., are not required.
Therefore, research into methods of reinforcing soft ground have been recently conducted regularly so that when a structure is constructed on soft ground which has insufficient bearing capacity, settlement can be prevented from being induced. A top-base method is a representative example of such soft ground reinforcement methods.
The top-base method is called a top-base foundation method, a concrete top-base foundation method, a concrete top-base type method, a concrete top type mat foundation method, a top-base mat foundation method, etc.
The top-base method is a soft-ground-surface treatment method for enhancing the bearing capacity of the ground and decreasing settlement when a structure is constructed on soft ground.
In the top-base method, top bases to which a load has been applied use location rods and connection rods which are arranged with the top bases to confine and compress the crushed stones they have been filled with and provide a reinforcing effect. This reinforces the ground foundation. The top-base foundation for ground surface treatment prevents lateral deformation and restrains settlement and differential settlement.
This top-base method is used, in place of a pile foundation method, to construct a medium or small structure the load of which is comparatively not large. The top-base foundation can enhance the bearing capacity of the ground and reduce settlement. Regardless of the conditions of a construction site or the use of large equipment, the construction time can be shortened, and over-design is prevented, so that efficient foundation work can be realized.
Furthermore, in the top-base method, a conical part having a top shape increases the area of contact and thus distributes the surface load, and embedment resistance of a pile part which embeds into the ground enhances the bearing capacity of the ground and reduces settlement of the ground.
As shown in FIG. 2, the top-base foundation includes top bases, location rods, connection rods and filling crushed stones. Each top base includes a conical part and a pile part. In an embodiment, the top surface of the top base has a diameter of 500 mm. The location rods function to guide the top bases at a correct installation position and serve as reinforcing bars. Mesh reinforcement is used as the location rods. The connection rods function to connect the top bases to each other in a lattice shape. Each connection rod has the same size as that of the location rod. The crushed stones, such as crushed gravels or the like, are used as a filler and charged into the space among the top bases. Moreover, before the location rods are arranged, sand and geotextile may be paved to separate the crushed stones from the soil and additionally increase the effect of improving the bearing capacity and restriction of settlement (refer to FIGS. 3 and 4).
When application of the pile foundation method causes over-design, it is advantageous to use the top-base method for the sake of economical efficiency. In addition, the top-base method can be conducted even in small construction sites. Furthermore, equipment used in the top-base method is comparatively simple. The top-base method is an environmentally friendly method, which generates neither noise nor vibration.
However, in the conventional top-base method, when settlement of the top-base foundation is determined, an influential depth to which settlement occurs is determined in a ratio of 1:1 to a footing configuration without taking into account consolidation settlement which may occur after the construction of the top-base foundation has been completed. Thus, the settlement determined by the conventional top-base method may differ greatly from the actual settlement of the construction site.